Anticavitation device



Dec. 2, 1969 J. D. LAYFIELD E 3,481,114

ANTICAVITATION DEVICE Filed April 15. 1968 INVENTORS ,Zy/e @flkyer/ana BY Jam a! fl layf//a United States Patent 3,481,114 ANTICAVITATION DEVICE James David Layfield, Honolulu, Hawaii, and Lyle v Robert Slingerland, Wellsville, N.Y., assignors to The Air Preheater Company, Inc., Wellsville, N.Y., a corporation of Delaware Filed Apr. 15, 1968, Ser. No. 721,356 Int. Cl. B01d 53/00 U.S. Cl. 55-159 9 Claims ABSTRACT OF THE DISCLOSURE The housing of a liquid-gas contacting deivce with a liquid inlet port and a liquid outlet port has an anticavitation chamber which substantially encloses a lower corner portion of the housing, including the outlet port. The chamber has an inlet opening adjacent the housing floor for rapid withdrawal of liquid from the housing and, in a conduit connecting a pump to the outlet port, a vent for releasing air trapped at the top of the chamber.

BACKGROUND OF THE INVENTION Cavitation is the partial vaporization of fluid in a stream causing vapor pockets in the fluid that collapse and produce vibrations, noise and destruction to the surrounding structure. Since cavitation is caused by the reduction in absolute pressure of the fluid and its relation to the free oxygen therein, this phenomenon will usually begin in the suction passages of the apparatus involved.

SUMMARY OF THE INVENTION To reduce the damaging effects of cavitation in a housing containing a source of fluid under a negative pressure or suction, there is hereby provided a devicethat avoids cavitation by reducing to a minimum the free oxygen contained in the fluid. Moreover the device of the invention is both effective in operation and economically produced.

For better understanding of the invention reference may be taken to the accompanying drawing in which:

FIGURE 1 is a typical arrangement of a cooling tower system involving the use of the apparatus disclosed,

FIGURE 2 is a perspective view, partially broken away to show a preferred form of the invention, and

FIGURE 3 is a perspective view of a modified form of the invention.

In the drawing the reference numeral designates a housing of a cooling tower or the like receiving a continuous flow of liquid which colletcs at the bottom thereof and is withdrawn through an outlet 12 adjacent the lower corner of said housing. Several properties of the liquid being withdrawn from the housing such as the temperature or vapor pressure thereof may affect the intensity of its cavitation damage, however the air content of said liquid is perhaps the most fundamental factor as the variation in its cavitation susceptibility is directly related to its air content. Moreover it is the dispersed air rather than dissolved air which facilitates cavitation.

To preclude the inclusion of excess air in the liquid that is being withdrawn from the housing and to thus reduce its tendency toward cavitation, an arrangement is provided whereby fluid collecting at the bottom of the housing is withdrawn therefrom in a thin layer remote from the ambient air and thus substantially free from having dispersed air contained therein.

In accordance with the invention the anti-cavitation deivce comprises a triangular plate 14 fitted into a corner of the housing 10 and having one edge 16 thereof substantially tangent to the periphery of the outlet port 12 and essentially parallel to the housing floor 18. It is moreover adapted to extend along t he wall of the housing at least as far as and preferably somewhat farther than its point of tangency 22 with the outlet port 12. A second edge 24 of the triangular plate 14 abuts the adjoining wall of the housing and is parallel to the housing floor 18 or declines downwardly from the edge 16 thereof to produce the top of a chamber 35 having a single outlet 12 adjacent thereto whereby bleed valve 62 may be positioned at the uppermost level of the P rt to bleed entrapped air from the chamber.

A second plate 26 has an edge thereof substantially equal in length to that of the free edge of the triangular plate 14. The plate 26 abuts the free edge of the triangular plate 14 and declines from the upper edge 28 thereof toward the floor of the housing but terminates above the floor to form therewith an elongate inlet port 32 to thechamber 35 formed by the Walls of the housing and the plates 14 and 26. The edges 34 and 36 of the plate 26 abut the converging housing walls and are bonded thereto in fixed relation along with abutting edges of the plate 14 to form the chamber 35 having the inlet port 32 and the outlet port 12.

The area of the elongate port 32 is at least as large as that of the outlet port 12 in order that the velocity of fluid flow into and out of chamber 35 may be maintained substantially the same for all conditions of fluid flow.

A screen 38 is positioned over the anticavitation device as defined to serve as a strainer to effectively remove the larger particles of foreign matter from the liquid stream flowing from the housing into the anticavitation chamber and out the outlet port 12 into the ilne 42 leading to the pump 44.

The screen 38 is preferably arranged so as to be readily accessible for easy cleaning through a nearby access door 46. Thus the screen may be shaped to be hung from or inclined against the plate 26 in the manner shown by FIGURE 2 or it may, for example as in FIG- URE 3, have a triangular configuration with one side 48 thereof positioned adjacent the floor while the converging sides abut the housing walls sapced from but adjacent those of plate 26. A pair of positioning blocks 56 secured to the floor of the housing as by welding provide stop means for the screen 38 whereby it may be readily removed and replaced for continuous operation.

The anticavitation device is used to advantage in the housing of a device such as the cooling tower of FIGURE 1 in which water to be cooled enters the hOusing 10 through inlet pipes 4 is sprayed out nozzles 6 and allowed to flow downward over the contacting surface 8 and allowed to collect at the bottom of the housing. Ambient air to contact the flowing water as it trickles over the fill or contacting surface 8 is drawn into the housing 10 by fan 9 and exhausted through port 11 after having contacted the water and absorbed a significant portion of the heat contained thereby.

The outlet port 12 is connected by means of a duct 42 to a pump means 44 by which fluid which has been cooled by contact with the air and collected at the bottom of the chamber 35 may be Withdrawn therefrom and directed as desired to be re-used as substantially cool, fresh, cooling fluid.

The vent valve 62 positioned near the outlet port 12 at an easily accessible location adjacent the highest point of chamber 35 permits bleeding trapped air therefrom thus substantially reducing the tendency for the inclusion of air in the suction fluid and its cavitation when the fluid is being withdrawn from the chamber 35 by the pump 44.

Before being placed in operation, cooling fluid is allowed to collect at the bottom of the housing 10 until it attains a depth in the housing somewhat above the level of the top of the anticavitation chamber and the upper edge of the outlet port 12. Vent valve 62 is accordingly opened and air entrapped within the chamber 35 is vented to the atmosphere until the chamber is filled with fluid and there exists a substantial absence of free air above the fluid. At this point the vent valve is closed, the pump is started, and air-free fiuid is withdrawn from the housing by the circulating pump substantially free from the effects of cavitation.

In the practice the plates 14 and 26 may be comprised of a single metallic plate bent along a line 28 and then welded to the walls of the housing 10 to comprise the top and side wall of an anticavitation chamber 35 as defined. The plate 26 might well be replaced by a triangular palte 30 in the manner shown by FIGURE 3 the critical feature being the arrangement by which a bleed valve 62 is positioned at the highest point of the chamber 35 whereby all entrapped air may easily be removed therefrom and the fluid allowed to fill the chamber 35 and the duct 15.

While this invention has been described with reference to the various embodiments illustrated in the drawing, it is evident that other modifications may be made without departing from the spirit of the invention. It is therefore intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative only and not in a limiting way.

We claim:

1. An anticavitation device in a housing having an inlet port for the supply of fluid thereto and an outlet port adjacent a lower corner thereof for the exhaust of fluid therefrom, said anticavitation device comprising a triangular plate having a substantially horizontal edge thereof abutting a wall of said housing arranged to subtend a portion thereof that includes the outlet port, a second edge of said triangular plate arranged in an abutting relation with another wall of said housing, an inclined plate having one edge thereof secured to the free edge of said triangular plate and an adjoining edge thereof secured to the housing wall to provide a wall for an anticavitation chamber adjacent said outlet port, said inclined plate having the lower edge thereof lying in spaced relation with the floor of said housing to provide an elongate inlet port to the chamber lying adjacent said housing floor.

2. A housing having an inlet port f r the supply of fluid thereto and an outlet port adjacent a lower corner thereof for the exhaust of fluid therefrom, an anticavitation device in said housing arranged to subtend a portion of said housing that includes the outlet p rt,

said anticavitation device comprising a substantially horizontal triangular plate abutting the walls of said housing and lying adjacent the upper edge of the outlet port, and a second plate having an edge thereof bonded to the free edge of said triangular plate and adjacent side edges thereof bonded to said housing walls to form an anticavitation chamber enclosing the corner of said housing including the outlet port, the lowest edge of the second plate arranged to lie in spaced relation to the floor of said housing to provide an elongate inlet port to the anticavitation chamber lying adjacent the bottom of the housing.

3. An anticavitation device as defined in claim 2 wherein the area of said elongate inlet port to the anticavitation chamber is substantially equal to the area of said outlet therefrom.

4. An anticavitation device as defined in claim 2 wherein the second plate is of trapezoidal configuration.

5. A device as defined in claim 2 wherein the anticavitation device is enclosed in a housing whose sides are of substantially rectangular configuration.

6. An anticavitation device as defined in claim 2 wherein the second plate is of trapezoidal configuration having the shorter of its parallel sides bonded to the free edge of said triangular plate and the oblique sides thereof bonded to the housing walls.

7. An anticavitation device as defined in claim 2 wherein the triangular plate is essentially tangent to the upper edge of the outlet port.

8. An anticavitation device as defined in claim 2 including means for maintaining a liquid level therein means for venting air trapped at the top of said chamber above said liquid level.

9. An anticavitation device as defined in claim 8 including a pump having an inlet, and duct means connecting the outlet port of said housing with the inlet port of said pu-mp.

References Cited UNITED STATES PATENTS 2,872,168 2/1959 Mart 261-30 REUBEN FRIEDMAN, Primary Examiner R. W. BURKS, Assistant Examiner US. Cl. X.R. 261-34 

